I hate endings like this

I guess if you lack the intellectual capacity to understand everything a little more intricate than your toaster, you would indeed be upset and annoyed at your own inadequacies.

Come to think of it, the workings of your toaster are probably beyond you as well.

My interpretation was that once the ritual was completed, the "darkness" was set free- it could go anywhere now, and was not contained within the house. The force could wreak havoc wherever it wanted now, and claim however many lives it wanted. So, yes, presumably, it did take over the world, but the movie never went that far with it, it left us to make up our own minds of what followed. All we know for absolute sure (in context of the movie) is that it did in fact claim Regina, Paul, their mother, and Carlos.

"They say that time changes things, but you actually have to change them yourself."
- Andy Warhol

kind of like this existence, actually. right underneath the surface of civility, lies a lot of evil in a lot of people. actually, sometimes evil people can really rule for awhile or oppress good people. it's literally like they are agents of the devil or evil. it plays out in real life too. it's just that good and bad tend to go in cycles as one has more leverage at a certain time and vice versa. for instance, back in the '80's rightwing dark spirited people were much more in power than today which is more enlightened.

Please explain what happened then, with your brilliant imagination.

Just understand it will only be your personal opinion, as the OP noted. Because the film doesn't explain, or even really indicate, what actually happened.

(If it took over the world, why bother to trick the kids?)

That's one of the reasons it sucks.

If people wanted to use their imagination then they wouldn't have watched a movie to begin with. A movie is a story that's told to you. It's supposed to be the writer, director and cast's imagination, not the viewers.